scholarly journals Was the Laurentide Ice Sheet significantly reduced during Marine Isotope Stage 3?

Geology ◽  
2019 ◽  
Vol 47 (2) ◽  
pp. 111-114 ◽  
Author(s):  
April S. Dalton ◽  
Sarah A. Finkelstein ◽  
Steven L. Forman ◽  
Peter J. Barnett ◽  
Tamara Pico ◽  
...  
Keyword(s):  
Ice Sheet ◽  
Marine Isotope Stage ◽  
Laurentide Ice Sheet ◽  
Marine Isotope Stage 3

scholarly journals Was there a glacial outburst flood in the Torngat Mountains during Marine Isotope Stage 3?

2021 ◽  
Author(s):  
Tamara Pico ◽  
Jane Willenbring ◽  
April S. Dalton ◽  
Sidney Hemming
Keyword(s):  
Ice Sheet ◽  
High Elevation ◽  
Marine Isotope Stage ◽  
Laurentide Ice Sheet ◽  
Freshwater Flux ◽  
Outburst Flood ◽  
Mis 3 ◽  
Flood Volume ◽  
Marine Isotope Stage 3 ◽  
Exposure Ages

Abstract. We report previously unpublished evidence for a Marine Isotope Stage 3 (MIS 3; 60–26 ka) glacial outburst flood in the Torngat Mountains (northern Quebec/Labrador, Canada). We present 10Be cosmogenic exposure ages from legacy fieldwork for a glacial lake shoreline with evidence for outburst flooding in the Torngat Mountains, with a minimum age of 36 ± 3 ka (we consider the most likely age, corrected for burial, to be ~56 ± 3 ka). This shoreline position and age can potentially constrain the Laurentide Ice Sheet margin in the Torngat Mountains. This region, considered a site of glacial inception, has no published dated geologic constraints for high-elevation MIS 3 ice margins. We estimate the freshwater flux associated with the inferred glacial outburst flood using high-resolution digital elevation maps corrected for glacial isostatic adjustment. Using assumptions about the ice-dammed locations we find that a freshwater flood volume of 1.14 × 1012 m3 could have entered the Hudson Strait. This glacial outburst flood volume could have contributed to surface ocean freshening to cause a measurable meltwater signal in δ18O records, but would not necessarily have been associated with substantial ice rafted debris. Future work is required to refine estimates of the size and timing of such a glacial outburst flood. Nevertheless, we outline testable hypotheses about the Laurentide Ice Sheet and glacial outburst floods, including possible implications for Heinrich events and glacial inception in North America, that can be assessed with additional fieldwork and cosmogenic measurements.

scholarly journals Submarine melt as a potential trigger of the North East Greenland Ice Stream margin retreat during Marine Isotope Stage 3

2019 ◽  
Vol 13 (7) ◽  
pp. 1911-1923 ◽  
Author(s):  
Ilaria Tabone ◽  
Alexander Robinson ◽  
Jorge Alvarez-Solas ◽  
Marisa Montoya
Keyword(s):  
Three Dimensional ◽  
Ice Sheet ◽  
High Sensitivity ◽  
Marine Isotope Stage ◽  
Atmospheric Conditions ◽  
North East ◽  
Ice Stream ◽  
Grounding Line ◽  
Oceanic Forcing ◽  
Marine Isotope Stage 3

Abstract. The Northeast Greenland Ice Stream (NEGIS) has been suffering a significant ice mass loss during the last decades. This is partly due to increasing oceanic temperatures in the subpolar North Atlantic, which enhance submarine basal melting and mass discharge. This demonstrates the high sensitivity of this region to oceanic changes. In addition, a recent study suggested that the NEGIS grounding line was 20–40 km behind its present-day location for 15 ka during Marine Isotope Stage (MIS) 3. This is in contrast with Greenland temperature records indicating cold atmospheric conditions at that time, expected to favour ice-sheet expansion. To explain this anomalous retreat a combination of atmospheric and external forcings has been invoked. Yet, as the ocean is found to be a primary driver of the ongoing retreat of the NEGIS glaciers, the effect of past oceanic changes in their paleo evolution cannot be ruled out and should be explored in detail. Here we investigate the sensitivity of the NEGIS to the oceanic forcing during the last glacial period using a three-dimensional hybrid ice-sheet–shelf model. We find that a sufficiently high oceanic forcing could account for a NEGIS ice-margin retreat of several tens of kilometres, potentially explaining the recently proposed NEGIS grounding-line retreat during Marine Isotope Stage 3.

scholarly journals Equilibrium simulations of Marine Isotope Stage 3 climate

2019 ◽  
Vol 15 (3) ◽  
pp. 1133-1151 ◽  
Author(s):  
Chuncheng Guo ◽  
Kerim H. Nisancioglu ◽  
Mats Bentsen ◽  
Ingo Bethke ◽  
Zhongshi Zhang
Keyword(s):  
Sea Ice ◽  
Ocean Circulation ◽  
Large Scale ◽  
Ice Sheet ◽  
Arctic Sea Ice ◽  
Meridional Overturning Circulation ◽  
Marine Isotope Stage ◽  
Quasi Equilibrium ◽  
Near Surface ◽  
Marine Isotope Stage 3

Abstract. An equilibrium simulation of Marine Isotope Stage 3 (MIS3) climate with boundary conditions characteristic of Greenland Interstadial 8 (GI-8; 38 kyr BP) is carried out with the Norwegian Earth System Model (NorESM). A computationally efficient configuration of the model enables long integrations at relatively high resolution, with the simulations reaching a quasi-equilibrium state after 2500 years. We assess the characteristics of the simulated large-scale atmosphere and ocean circulation, precipitation, ocean hydrography, sea ice distribution, and internal variability. The simulated MIS3 interstadial near-surface air temperature is 2.9 ∘C cooler than the pre-industrial (PI). The Atlantic meridional overturning circulation (AMOC) is deeper and intensified by ∼13 %. There is a decrease in the volume of Antarctic Bottom Water (AABW) reaching the Atlantic. At the same time, there is an increase in ventilation of the Southern Ocean, associated with a significant expansion of Antarctic sea ice and concomitant intensified brine rejection, invigorating ocean convection. In the central Arctic, sea ice is ∼2 m thicker, with an expansion of sea ice in the Nordic Seas during winter. Attempts at triggering a non-linear transition to a cold stadial climate state, by varying atmospheric CO2 concentrations and Laurentide Ice Sheet height, suggest that the simulated MIS3 interstadial state in the NorESM is relatively stable, thus underscoring the role of model dependency, and questioning the existence of unforced abrupt transitions in Greenland climate in the absence of interactive ice sheet–meltwater dynamics.

scholarly journals Chronology of advance and recession dynamics of the southern Green Bay Lobe of the Laurentide Ice Sheet, south-central Wisconsin, USA

2020 ◽  
Vol 95 ◽  
pp. 142-153
Author(s):  
Eric C. Carson ◽  
John W. Attig ◽  
J. Elmo Rawling ◽  
Paul R. Hanson ◽  
Stefanie E. Dodge
Keyword(s):  
Ice Sheet ◽  
Marine Isotope Stage ◽  
Laurentide Ice Sheet ◽  
Time Interval ◽  
Green Bay ◽  
Ams Radiocarbon Dating ◽  
South Central ◽  
Southern Margin ◽  
Osl Age ◽  
Age Estimates

AbstractWe used a combination of accelerator mass spectrometry (AMS) radiocarbon dating, optically stimulated luminescence (OSL) age estimates, and stratigraphic data from cores collected along the southern margin of the Green Bay Lobe (GBL) of the Laurentide Ice Sheet to provide new information on the timing and dynamics of the end of advance of the GBL and the dynamics of the ice sheet while very near its maximum position. Coring at multiple sites along the margin of the GBL indicate that ice had reached a stable position near its maximum extent by 24.7 ka; that ice advanced several kilometers to the Marine Isotope Stage 2 maximum position sometime shortly after 21.2 ka; and that ice remained at or beyond that position through the time interval represented by an OSL age estimate of 19.2 ± 3.2 ka. The timeline developed from these chronological data is internally consistent with, and further refines, AMS radiocarbon ages and OSL age estimates previously published for the southern margin of the GBL. It also provides new chronological control on the expansion of the GBL from its late Marine Isotope Stage (MIS) 3 extent to its MIS 2 maximum.

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